The U.S. Air Force has restarted its effort to replace 62 Vietnam War-vintage UH-1N Huey helicopters with a commercially available helicopter by 2015, according to a Dec. 17 service document.

The sources-sought notice seeks contractors who can provide the Air Force with up to 93 helicopters - dubbed the Common Vertical Lift Support Platform (CVLSP) - that can carry at least nine passengers and that have proved themselves in commercial or government service. The service wants to put the new helicopters into service quickly: "We will consider some performance trade offs to meet schedule at an affordable cost."

The Air Force expects to award a contract for the helicopters as soon as fiscal year 2012 and wants to have at least six aircraft by 2015, the target date for initial operational capability. Another 10 choppers are due no later than Sept. 30, 2017.

One way the service hopes to do this is by purchasing an aircraft that is currently in production, according to the document.

The service's UH-1N fleet dates to the 1970s and is used primarily at nuclear missile bases in Montana, North Dakota and Wyoming, where they patrol missile fields, fly search-and-rescue missions, and more. The Air Force has another squadron of Hueys at Andrews Air Force Base, Md., that provide VIP airlift around Washington. The Sixth Special Operations Squadron also flies a handful of the aircraft for special operations missions at Hurlburt Field, Fla.

Those aircraft fly a cruising speed of roughly 100 knots and can carry up to 13 passengers depending on the situation.

While the missions flown by the current Huey fleet are relatively benign, the service is looking for a helicopter with a fairly high degree of survivability in combat situations, according to the notice.

The new choppers must be armored against 7.62mm small arms fire, feature electro-optical and infrared sensors, infrared countermeasures, be night-vision-goggle ready, and carry enough firepower to dispatch several enemy infantry squads during one mission, according to the notice.

The Air Force also wants the aircraft to be equipped with secure satellite communications as well as nonsecure line-of-sight communications links.

In addition to carrying nine passengers or 3,195 pounds of cargo, the CVLSP birds must be able to maintain a minimum of 135 knots airspeed while flying at 6,500 feet and be able to fly for at least three hours unrefueled at 6,500 feet.

The Army is replacing its antiquated Hueys with 345 EADS-built UH-72 Lakotas in a multiyear contract estimated to cost $3 billion. The Army uses the unarmed Lakota for stateside missions such as medical evacuations, drug hunting and personnel transport.